KRT88P and thalassemia: Mutant genotypes were common for all polymorphisms studied, except HbC, with many more heterozygous than homozygous alleles identified (Table 2).Among community controls, allele frequencies were 6.2% for HbS, 0% for HbC, 22.3% for α-thalassemia, and 10.2% for G6PDA; none of the allele distributions violated Hardy Weinberg equilibrium (S1 Table).